I have a new house with an unfinished basement. The rough in plumbing drains are there for everything but I have a question about the sink drain. There's a vertical 2" PVC pipe running where the rear wall of the basement bathroom will go. On the bathroom side the plumber put in a threaded cleanout that would get blocked by the vanity so there wouldn't be any access to it later. Is that threaded connection there for me to tie the sink drain to?